Hoi is a thief that stole money from others by impersonating Riou. However, he was discovered and beaten up along with Riou who was mistaken as an accomplice. That prompted him to join the Unification Army. - Blue Moon

Gameplay Information for Suikoden II

How to Recruit: Speak to him at the restaurant in Radat.
Note: Available any time after defeating Luca Blight.